Air conditioners are generally arranged in a certain space, such as rooms, living rooms, offices, and stores, to adjust the temperature, moisture, clearness, and air flow to maintain inner environment clean and fresh.
An air conditioner may be commonly classified into an integral type and a stand-alone type. Both types are the same in their functions. In the integral type air conditioner, however, a cooling function has been integrated with a heating function, and the air conditioner is mounted on the wall or window. On the contrary, the stand-alone type air conditioner includes an indoor unit and an outdoor unit that are provided separately from each other. The indoor unit is located indoors for providing heating and cooling. The outdoor unit is located outdoors for heat dissipation and compression. The indoor unit is coupled with the outdoor unit via a refrigerant pipe.
An air conditioner includes a motor used for a compressor or fan, and a motor controller for driving the motor. The motor controller converts AC utility power into DC power and then AC power having a constant frequency.
A typical air conditioner calculates a loading from the difference between room temperature and setup temperature to drive the compressor with a predetermined frequency based on the amount of load. The operation frequency of the compressor is set up to increase as the loading is high.
However, if the amount of load is over a predetermined level, the motor driving device, especially circuit elements included in the inverter, may be damaged, which causes unstable operations. Furthermore, various factors are not considered that affects a real loading, and this interferes with the efficient driving of the compressor according to the real variation in the amount of load.